How to Re-configure Nutanix CVM Memory in Nutanix AHV Cluster through Command Line

In some cases Nutanix AHV node’s Controller VM ( CVM) required more memory to enable advance functionality like compression or duplication or in case of memory contention issue or CVM have low memory cause struggling with low performance issue.

To change or re-configure the Nutanix Controller VM ( CVM ) is important to leverage the Nutanix cluster feature and high performance to increase the Nutanix CVM memory as per recommendation.

Additional CVM Memory for Add-on Features

The following table lists the minimum amount of memory required when enabling features.

The memory size requirements are in addition to the default or recommended memory available for your platform.

The maximum additional memory required is 16 GB even if the total indicated for the features is more than that.

Total CVM memory required = recommended platform memory + memory required for each enabled feature (max 16 GB)

Self-service portal (AHV only)

If you want to use Self-Service portal feature of Nutanix AHV Hypervisor then you need to know :

• SSP requires a minimum of 24 GB of memory for the CVM.
  If the CVMs already have 24 GB of memory, no additional memory is necessary to run SSP.
• If the CVMs have less than 24 GB of memory, increase the memory to 24 GB to use SSP.
• If the cluster is using any other features that require additional CVM memory, add 4 GB for SSP in addition to the amount needed for the other features.

Change CVM Memory Configuration in AHV Hypervisor

To changing the Nutanix Controller VM ( CVM ) memory there is procedure need to follow to change the Nutanix CVM memory configuration.

Follow step to step Nutanix CVM memory re-configuration procedure.

Step 1 : Log on to the AHV host with SSH

Step 2 : Find the name of the Nutanix Controller VM ( CVM )

root@ahv# virsh list --all | grep CVM

Note : Write down the Controller VM name will use it later steps

Step 3 : Log on to the Nutanix Controller VM with SSH

Step 4 : Safely shutdown the Nutanix Controller VM ( CVM)

nutanix@cvm$ cvm_shutdown -P now

Read more : How to Shutdown Nutanix AHV Host and Nutanix CVM

Step 5 : Log on to AHV host again and determine current memory and CPU settings

root@ahv# virsh dumpxml cvm_name | egrep -i "cpu|memory"

Step 6 : Change the memory configuration of the Nutanix Controller VM (CVM ) as per your requirement or to enable the advanced features as shown in above table.

root@ahv# virsh setmaxmem cvm_name --config --size ram_gbGiB
root@ahv# virsh setmem cvm_name --config --size ram_gbGiB

Example : I want to leverage the “Performance tier deduplication” feature and required 8GiB additional memory to enable this feature.

root@ahv# virsh setmaxmem cvm_name --config --size 8GiB
root@ahv# virsh setmem cvm_name --config --size 8GiB
Technical note : Replace ram_gb with required "memory number"GiB

Note : Replace Nutanix CVM_Name with the name of the Nutanix Controller VM that you noted down in step 2.

Read more : How to Change Nutanix CVM Host name

Step 7 : Power on the Nutanix CVM

root@ahv# virsh start cvm_name

Step 8 : Log on to the Nutanix Controller VM ( CVM ) again to confirm that cluster services are running on the Nutanix CVM

nutanix@cvm$ cluster status

Result should be positive to running all Nutanix CVM’ Components & services in the Nutanix acropolis AHV cluster.

Read more : How To Change Nutanix CVM, AHV and IPMI Passwords

Conclusion

To changing the Nutanix CVM memory is also possible from Prism but doesn’t give flexibility to customize the memory size as per your own requirement. I would suggest you can use both methods : command line or Prism GUI to re-configure the Nutanix CVM memory.

But be careful to run any command without knowledge it might cause impact on Nutanix system.

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